The present invention relates to an assembling arrangement for a tensioner and a hydraulic control valve in an internal combustion engine. In addition, the present invention relates to an oil passage arrangement for supplying an oil pressure to a tensioner for a camshaft driving chain. Further, the present invention relates to a mounting structure of a hydraulic control valve in the internal combustion engine.
In engines in which the rotation of a crankshaft is transmitted to a camshaft via a chain/sprocket mechanism, an engine is known which uses a tensioner using a plunger adapted to be pushed out by virtue of oil pressure in order to maintain the tension of a chain constant (refer to Japanese Utility Model Registration No. 2503434).
A tensioner such as described above, however, requires an oil passage to be formed so as to supply an oil pressure for imparting a thrust to the plunger in response to the slackness of the chain and an oil filter to be provided so as to prevent the intrusion of sludge or the like into the oil passage so formed. This construction has created a need for reducing production costs of such engines. This is a first problem in the conventional technique.
In addition, an engine has been put into practical use which is provided with a variable valve train as hydraulically controlled equipment in which intake and exhaust valve operation timings are automatically variable in response to the running condition of the engine, and cars equipped with the variable valve train are already sold in the market place.
This variable valve train is adapted to select connection or disconnection between a plurality of rocker arms pivotally supported on a rocker shaft using a switch-over device for hydraulic operations, and this valve train requires a control valve for connecting and/or disconnecting the oil pressure to be applied to the switch-over device and an oil passage for supplying the oil pressure to the switch-over device via the control valve (refer to JP-B-9-10104U).
In the aforesaid prior art, the control valve is attached to an end surface of a cylinder head on a transmission side thereof or an end surface opposite to a mounting surface where a camshaft driving mechanism is mounted.
An engine compartment of a small-sized car is more spacious in a transverse direction than in a longitudinal direction, and therefore, with a transversely mounted engine in which the crankshaft is made parallel with the axle, the serviceability for maintenance can be secured by providing the control valve on an end surface of the cylinder head on a transmission side in a direction of the crankshaft, or an end surface opposite to a mounting surface where the camshaft driving mechanism is mounted. With a longitudinally mounted engine in which the crankshaft is disposed perpendicular to the axle, considering the serviceability for maintenance in the engine compartment, it is difficult to provide the control valve on the rear end surface of the cylinder head in the crankshaft direction or on the end surface on the transmission side.
It is further difficult to mount the control valve on the side of the cylinder head or cylinder block where in intake manifold and the exhaust manifold are mounted at a position causing no problem with servicing for maintenance. In addition, if the control valve were to be so mounted, it will tend to result in the enlargement of the engine in size.
It is possible to try to provide the control valve at a position spaced away from the engine main body, but if such is tried, it will inevitably result in an increase in man hours for production. This is a second problem in the conventional technique.